This invention is generally directed to photoresponsive imaging members, and more specifically the present invention is directed to photoresponsive imaging members containing therein as photogenerating pigments chloroindium phthalocyanine compositions. Thus, in one embodiment, the present invention envisions the use of chloroindium phthalocyanine compositions of matter as photogenerating pigments in photoresponsive imaging members having incorporated therein specific arylamine hole transport molecules. In another embodiment of the present invention there are provided photoresponsive imaging members with a photogenerating layer comprised of the chloroindium phthalocyanine compositions disclosed herein, and a photoconductive layer, enabling the resulting members to possess photosensitivity in the wavelength region of from about 400 to about 900 nanometers. Imaging members with the chloroindium phthalocyanine compositions of the present invention are useful in electrophotographic imaging and printing systems, especially xerographic systems, wherein the resulting members are sensitive to visible light, and infrared illumination needed for laser printing.
Numerous different xerographic photoconductive members are known including, for example, a homogeneous layer of a single material such as vitreous selenium, or a composite layered device consisting of a dispersion of a photoconductive composition. An example of a composite xerographic photoconductive member is disclosed in U.S. Pat. No. 3,121,006, wherein there is illustrated finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in this patent comprise a material which is incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles. Accordingly, as a result, the photoconductive particles must be in a substantially contiguous particle-to-particle contact throughout the layer for the purpose of permitting charge dissipation required for a cyclic operation. Thus, with the uniform dispersion of photoconductive particles described, a relatively high volume concentration of photoconductor material, about 50 percent by volume, is usually necessary in order to obtain sufficient photoconductor particle-to-particle contact for rapid discharge. This high photoconductive loading can result in destroying the physical continuity of the resinous binder, thus significantly reducing the mechanical properties thereof. Illustrative examples of specific binder materials disclosed in the '006 patent include, for example, polycarbonate resins, polyester resins, polyamide resins, and the like.
There are also known photoreceptor materials comprised of inorganic or organic materials wherein the charge carrier generating, and charge carrier transport functions, are accomplished by discrete contiguous layers. Additionally, layered photoreceptor materials are disclosed in the prior art which include an overcoating layer of an electrically insulating polymeric material. However, the art of xerography continues to advance and more stringent demands need to be met by the copying apparatus in order to increase performance standards, and to obtain higher quality images.
Recently, there has been disclosed other layered photoresponsive imaging members including those comprised of separate generating layers, and transport layers, reference U.S. Pat. No. 4,265,990, and overcoated photoresponsive materials containing a hole injecting layer, overcoated with a hole transport layer, followed by an overcoating of a photogenerating layer, and a top coating of an insulating organic resin, reference U.S. Pat. No. 4,251,612. Examples of photogenerating layers disclosed in these patents include trigonal selenium and phthalocyanines, while examples of transport layers include certain diamines as mentioned herein. The disclosures of each of these patents, namely, U.S. Pat. Nos. 4,265,990 and 4,251,612, are totally incorporated herein by reference.
Many other patents are in existence describing photoresponsive members, reference U.S. Pat. No. 3,041,167, which discloses an overcoated imaging member with a conductive substrate, a photoconductive layer, and an overcoating layer of an electrically insulating polymeric material. This member is utilized in an electrophotographic copying method by, for example, initially charging the member, with an electrostatic charge of a first polarity, and imagewise exposing to form an electrostatic latent image which can be subsequently developed to form a visible image. Prior to each succeeding imaging cycle, the imaging member can be charged with an electrostatic charge of a second polarity, which is opposite in polarity to the first polarity. Sufficient additional charges of the second polarity are applied so as to create across the member a net electrical field of the second polarity. Simultaneously, mobile charges of the first polarity are created in the photoconductive layer by applying an electrical potential to the conductive substrate. The imaging potential which is developed is present across the photoconductive layer and the overcoating layer.
There is also disclosed in Belgium Pat. No. 763,540, an electrophotographic member having at least two electrically operative layers, the first layer comprising a photoconductive layer which is capable of photogenerating charge carriers, and injecting the carriers into a continuous active layer containing an organic transporting material which is substantially nonabsorbing in the spectral region of intended use, but which is active in that it allows the injection of photogenerated holes from the photoconductive layer and allows these holes to be transported through the active layer. Additionally, there is disclosed in U.S. Pat. No. 3,041,116, a photoconductive material containing a transparent plastic material overcoated on a layer of vitreous selenium contained on a substrate.
Furthermore, there is disclosed in U.S. Pat. Nos. 4,232,102 and 4,233,383, photoresponsive imaging members comprised of trigonal selenium doped with sodium carbonate, sodium selenite, and trigonal selenium doped with barium carbonate, and barium selenite or mixtures thereof.
Additionally, the use of squaraine pigments in photoresponsive imaging devices is known, reference for example U.S. Pat. No. 4,415,639, the disclosure of which is totally incorporated herein by reference, wherein there is described an improved photoresponsive device comprised of a substrate, a hole blocking layer, an optional adhesive interface layer, an organic photogenerating layer, a photoconductive composition capable of enhancing or reducing the intrinsic properties of the photogenerating layer, and a hole transport layer. As photoconductive compositions for this device, there can be selected various squaraine pigments, including hydroxy squaraine compositions of the formula as outlined on page 13, beginning at line 21, of the copending application. The imaging member of this patent is useful in electrophotographic imaging and printing systems, in that the member is sensitive to wavelengths of from about 400 to in excess of 800 nanometers. Moreover, there is disclosed in U.S. Pat. Nos. 3,824,099 and 4,390,610, certain photosensitive hydroxy squaraine compositions. According to the disclosure of the '610 patent, the squaraine compositions are photosensitive in normal electrostatographic imaging systems.
The use of certain selected perylene pigments as photoconductive substances is also known. There is thus described in Hoechst, European Patent Publication No. 0040402, BE3019326, filed 5/21/80, the use of N,N'-disubstituted perylene-3,4,9,10,-tetracarboxyl diimide pigments as photoconductive substances. Specifically, there is disclosed in this publication dual layered photoreceptors, with improved spectral response in the wavelength region of 400 to 700 nanometers containing evaporated N,N'-bis(3-methoxypropyl)perylene-3,4,8,10 tetracarboxyldiimide. It is important to note that these perylenes are insoluble pigments, accordingly photoconductive devices with such compositions must be prepared by vacuum evaporation techniques. A similar disclosure is illustrated in Ernst Gunther Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No. 3, page 118 (1978). Also, dual layered photoreceptors prepared from the perylene pigments as described in the above mentioned 0040402 publication can only be charged negatively thus requiring the use of positively charged toner compositions.
Moreover, there is disclosed in U.S. Pat. No. 4,419,427 electrophotographic recording mediums with a photosemiconductive double layer comprised of a first layer containing charge carrier producing dyes, and a second layer containing one or more compounds which are charge carrier transporting materials when exposed to light, wherein perylene diimides are employed as the charge carrier producing dyes. Examples of charge carrier transporting compounds disclosed in the '427 patent include pyrazoline derivatives, triphenylamines, and pyrene derivatives.
While many of the above-described imaging members are suitable for their intended purposes, there remains a need for improved members. Additionally, there continues to be a need for improved photogenerating materials possessing superior photosensitive properties, and wherein these pigments need not be dispersed in resinous binders when incorporated into a layered imaging member. Further, there continues to be a need for layered imaging members which require less light exposure in view of their high sensitivity, and wherein the resulting imaging members can be selected for use in high speed electrophotographic systems, particularly those generating copies of from about 60 to about 100 copies per minute. Also, there continues to be a need for layered imaging members comprised of the chloroindium phthalocyanine photogenerating compositions disclosed herein, and photoconductive substances, particularly organic substances such as perylene compositions, enabling the resulting members to be sensitive to wavelengths of from about 400 to about 900 nanometers. Further, there is a need for imaging members which are simultaneously useful for electrostatographic imaging systems sensitive to visible light, and printing systems wherein the resulting devices must possess sensitivity in the infrared region of the spectrum, that is exceeding about 750 nanometers.